Vitamin D Levels, Microvascular Complications, and Mortality in Type 1 Diabetes

Diabetes Care. 2011 May;34(5):1081-5. doi: 10.2337/dc10-2459.

Abstract

Objective: To evaluate vitamin D as a predictor of all-cause mortality, progression from normoalbuminuria to micro- or macroalbuminuria, and the development of background or proliferative retinopathy in patients with type 1 diabetes.

Research design and methods: A prospective observational follow-up study in which an inception cohort of type 1 diabetic patients was followed from onset of diabetes diagnosed between 1979 and 1984. Plasma vitamin D [25(OH)D3] levels were determined by high performance liquid chromatography/tandem mass spectrometry in 227 patients before the patients developed microalbuminuria. Values equal to or below the 10% percentile (15.5 nmol/L) were considered severe vitamin D deficiency.

Results: Median (range) vitamin D was 44.6 (1.7-161.7) nmol/L. Vitamin D level was not associated with age, sex, urinary albumin excretion rate (UAER), or blood pressure. During follow-up, 44 (18%) patients died. In a Cox proportional hazards model, the hazard ratio for mortality in subjects with severe vitamin D deficiency was 2.7 (1.1-6.7), P = 0.03, after adjustment for UAER, HbA(1c), and conventional cardiovascular risk factors (age, sex, blood pressure, cholesterol, smoking). Of the 220 patients, 81 (37%) developed microalbuminuria and 27 (12%) of these progressed to macroalbuminuria. Furthermore, 192 (87%) patients developed background retinopathy, whereas 34 (15%) progressed to proliferative retinopathy. Severe vitamin D deficiency at baseline did not predict the development of these microvascular complications.

Conclusions: In patients with type 1 diabetes, severe vitamin D deficiency independently predicts all-cause mortality but not development of microvascular complications in the eye and kidney. Whether vitamin D substitution in type 1 diabetic patients can improve the prognosis remains to be investigated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Albuminuria / blood
  • Chromatography, High Pressure Liquid
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 1 / mortality*
  • Female
  • Humans
  • Male
  • Prospective Studies
  • Tandem Mass Spectrometry
  • Vitamin D / blood*
  • Young Adult

Substances

  • Vitamin D